The invention is concerned with a fuel module for supplying fuel from a fuel tank to an internal combustion engine, having a feed pump which is used to take up fuel and feed it into a container, and having a main pump which takes up fuel from the container and supplies it at high pressure to the internal combustion engine, the feed pump being a pump which feeds at a low pressure and the pump outlet of which leads into the container via a fine filter.
In fuel modules of this type, it is known to arrange a fine filter in the line leading from the outlet of the main pump to the internal combustion engine. Although coarse filters are also frequently arranged on the main pump intake duct, these can only filter out particles from the fuel which are larger than approximately 40 to 100 μm. Smaller particles pass through the main pump and are filtered out only in the fine filter. This leads to problems if the moveable components of the main pump are arranged in the fixed components with only a small amount of play, so that gaps of the order of magnitude of only 10 to 20 μm are present between these components. These small gaps may become clogged up or damaged by the dirt particles which have passed through the coarse filter, with the result that the functioning of the main pump is impaired.
The replacement of the coarse filter on the main pump intake duct by a fine filter could be undertaken only with very large filter elements, since the soiling capacity which is possible over the lifetime of a motor vehicle would have to be in the region of several grams in order to ensure that the filter still allows a sufficient amount of flow to pass through it.
Since the suction action of the main pump is relatively small and lies in the region of only a few millibars, even with little soiling of the filter this suction action is no longer sufficient in order to take fuel into the pump to a sufficient extent, and so evaporation of the fuel in the fine filter occurs and thereby results in the pump having hot feeding problems which interfere with the functioning of the pump or even render it completely incapable of functioning.
DE-A-44 25 670 discloses a fuel module of the type mentioned at the beginning.
U.S. Pat. No. 47 70 150 discloses a fuel module for supplying fuel from a fuel tank to an internal combustion engine, the module having a feed pump which is used to take up fuel. The fuel is fed by the feed pump via a heat exchanger, a main filter and a fine filter to the injection pump of the internal combustion engine.
DE-A-198 46 616 discloses a fuel module for feeding fuel from a fuel tank to an internal combustion engine, the module having a feed pump which takes up fuel via a first filter and feeds it into a container. Fuel is taken up from the container via a fine filter by a main pump and supplied to the internal combustion engine.
It is the object of the invention to provide a fuel module of the type mentioned at the beginning which enables the use of main pumps of small dimensions, the functioning of which is ensured over their lifetime and in which there is no drop over the lifetime in the feed quantity of the fuel supplied to the internal combustion engine.
This object is achieved according to the invention by the fact that the container is a closed container in which the main pump is arranged.